Weaving

ABSTRACT

Yarn-handling mechanism for a textile machine comprising means for gripping each end of a length of yarn so that the length of yarn has a predetermined amount of slack, means for creating gaseous fluid flow along one or more portions of the length of yarn thereby to apply longitudinal force to that portion or portions of the yarn, application of the force in a first direction causing the yarn to be held in tension at a first location whilst the slack is formed at a second location and application of the force in the opposite direction causing the yarn to move so that the slack is transferred to the first location whilst the yarn is held in tension at the second location and means for positioning the slack portion of yarn in at least one of the locations to form a loop or shed.

[451 May 6,1975

United States Patent 11 1 Paton et al.

[ WEAVING [76] Inventors: Anthony David Paton, 51 Mills Lane, Longstanton St. Michael; Stephen Temple, 9 Almond Grove, Bar Hill, both of Cambridge, England [22] Filed: May 10, 1973 [21] APPL 353,910 prising means for gripping each end of a length of yarn so that the length of yarn has a predetermined amount of slack, means for creating gaseous fluid flow along Foreign Application Priflrily Data one or more portions of the length of yarn thereby to May 10, 1972 apply longitudinal force to that portion or portions of Jan. 26, 1973 United Kingdom. 21902/72 United Kingdom.................

4147/73 the yarn, application of the force in a first direction causing the yarn to be held in tension at a first loca- [52] US. 139/12; 139/55 tion whilst the slack is formed at a second location [51] Int. D0311 47/26 and application of the force in the opposite direction 12 causing the yarn to move so that the slack is trans- 226/97, 195 ferred to the first location whilst the yarn is held in [58] Field of Search........ 139/[1 tension at the second location and means for position- [56] References Cited ing the slack portion of yarn in at least one of the lo- UNITED STATES PATENTS cations to form a loop or shed.

2,870,349 1/1959 Rosenberg et 139/13 29 Claims, 21 Drawing Figures PATENTEUHAY 6I975 3.881523 sum QlUF 12 ob N mm SHEET PHENTED MAY 6 I975 FATENTEDHAY 5197s 3, 1,523 sum 03m 12 PATENTEBHAY 619. 5 3.881.523

sum 2? *JF 12 FIG. 9

255 210 204 222 44 50 L 206 K g FIG. 70

/2/4 ,2/0 205 mafia/4 1i 20' l 206 28 44 IE m. 12

PMENTEBM 6W5 3, 1,523

sum cm 12 zqa 2/0 234 206 2/4 44 mgpngmm 619. 5 1,523

SHEET (LS-1F 12 SHEET llUF 1 523 PiTEkTEE KAY 61'915 PSJEHTEE HAY 6 I575 SHEET 12UF 12 WEAVING This invention relates to yarn-handling mechanisms for textile machines.

It is often necessary in textile machines, such as knitting machines or weaving looms, to operate on one or more lengths of yarn to produce in the length or selected ones of the lengths of yarns a loop or shed, for example for the insertion into the loop or shed of a further yarn. In order to increase the speed of operation of the textile machine it is desirable to increase the speed of handling of such lengths of yarn, whilst retaining flexibility of pattern selection.

For example, in weaving looms it is necessary to act on the yarns of a warp yarn sheet to form sheds for the insertion of weft yarns. Hitherto, increases in the speed of operation of looms have been obtained by increasing the speed of weft insertion, as for example increasing the velocity of weft insertion in the rapier, grippershuttle and jet looms, or be providing multiple weft insertion in so-called multiphase looms in which warp yarns are shed successively in a wave motion across the loom with each shuttle or weft carrier moving in synchronism with the shedding wave. Developments of weft insertion have reached a limit, so that significant increases in the overall speed of operation of the loom can only be achieved by development of other aspects of the weaving operations such as warp shedding.

According to this invention there is provided yarnhandling apparatus for a textile machine comprising means for gripping each end ofa length of yarn so that the length of yarn has a predetermined amount of slack, means for creating gaseous fluid flow along one or more portions of the length of yarn thereby to apply longitudinal force to that portion or portions of the yarn, application of the force in a first direction causing the yarn to be held in tension at a first location whilst the slack is formed at a second location, and application of the force in the opposite direction causing the yarn to move so that the slack is transferred to the first location whilst the yarn is held in tension at the second location and means for positioning the slack portion of yarn in at least one of the locations to form a loop or shed.

The term yarn is intended to embrace monofilament yarns as well as multifilament or fibrous spun yarns or threads, and flat tape-like yarns such as used in woven backing fabrics for carpets.

Since the means by which the longitudinal forces are applied to the yarn have an extremely low inertia compared with the mechanical devices of conventional textile machines, for example the healds and beams of conventional weaving looms, the mechanism of the invention enables the yarn to be handled at higher speeds of operation.

In one form of the invention there is provided a loom comprising means for feeding a plurality of warp yarns to a shedding area, gripping means for gripping each end of a length of each warp yarn so that each length has a predetermined amount of slack, means for creating gaseous fluid flow along one or more portions of each of the lengths of warp yarn thereby to apply longitudinal force to the length of yarn, application of the force in a first direction urging the yarn to be held in tension in the shedding area whilst the slack is formed at a second location remote from the shedding area, and application of the force in a second direction urging the length of yarn to move so that the yarn in the shedding area is slack whilst the yarn is held in tension at the second location, means for separating the slack yarn in the shedding area from the warp to form a shed for the insertion of a weft yarn, and shedding control means for controlling the shedding operation of the warp yarns.

The invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings, in which:

FIG. 1 is a perspective view of a multiphase loom incorporating the invention,

FIG. 2 is a side elevation of the principal parts of the loom of FIG. 1,

FIG. 3 shows the shedding area of FIG. 2 on a larger scale,

FIG. 4 is a plan view of parts of the loom of FIGS. 1 and 2,

FIG. 5 is a side elevation of a weft carrier feed mechanism of the loom of FIGS. 1 to 3,

FIG. 6 is a vertical section through the shedding area of the loom of the preceding FIGS. showing the relative states of the shedding, beating and weft insertion operations at one instant in the weaving cycle,

FIG. 7 is a plan view of the shedding area shown in FIG. 6,

FIG. 8 is a timing diagram illustrating the relative timing of the various operations of the loom of FIGS. 1 to 5,

FIGS. 9 to 15 show diagrammatically alternative forms of shedding mechanism for use in the loom of FIGS. 1 to 5,

FIG. I6 is a section through a shedding mechanism fitted with an alternative form of shedding control,

FIG. 17 is a section through a shedding mechanism showing another alternative form of shedding control, and

FIG. 18 is a section along line AA of FIG. 17.

FIG. 19 is a side elevation of parts of a multiphase loom employing a reciprocating beater,

FIG. 20 is a fragmentary plan view of the loom of FIG. I9, and

FIG. 21 is a side elevation of parts of a further loom employing a reciprocating beater.

Referring to FIGS. 1 to 5, a multiphase loom comprises a set of driven feed rollers I0 by means of which warp yarns 20 are drawn off a beam 12 rotatably supported in suitable bearings, first and second arrays 14 and 16 of fluidic elements, described below, through which the warp yarns pass to reach a shedding area 18, a weft carrier transport mechanism for moving weft carriers, such as that shown at 22, through the shedding area during a picking operation, a beating mechanism 24, and a take-up roller 26 onto which the woven fabric is wound.

The arrays 14 and 16 of fluidic elements are divided in the weft direction into a number of similar sections, the warp yarns passing through each section being shed simultaneously, and the timing of the shedding of warp yarns in the various sections being controlled so that the sheds move across the warp sheet in a wave motion and a number of weft carriers can travel simultaneously across the warp sheet in the manner of a multiphase loom, as described more fully below.

Each section of the array 16 of fiuidic elements, as shown in FIG. 4, consists of an element 29 co-.tuining a number of parallel channels 30, one for each warp yarn passing through the element. A slit 32, of 0.003 inches depth, disposed at an acute angle of about 30 to the plane containing the channels 30 extends over the channels and provides a path to each channel from a manifold 34 a separate manifold being provided for each section of the array 16.

Extending from the mouths 36 of channels 30 is a flat surface 38 whose plane is inclined at 30 to the plane containing the channels 30. The Hat surface 38 is contiguous with a coplanar flat surface 40 which forms one face of a V-section track forming part 44 of the weft carrier transport mechanism, as described below. A flat surface 39 coplanar with surface 38 extends in the opposite direction from mouth 36.

A clanp 45 as shown in FIGS. 3 and 4, extend across the length of each element 29 of the array 16. The clamp 45 consists of an element which can be brought into engagement with the strands of warp yarn entering the channels 30 of thhe element 29 to hold the strands of warp yarn by binding the strands between the clamp 45 and the upper surface of a portion of channel 30. The clamp 45 can be actuated electromagnetically or pneumatically to engage all the warp yarns passing through element 29 to hold the yarns in the shedding area in tension during the beating operation.

From the mouth 36 of each channel 30, the portion 44 of yarn 20 extends to the fell 46 of the woven fabric 48, the fabric passing between fell guards 50 to the roll 26. The arrangement is such that, when the portion of yarn 44 is held in tension it makes an angle of to the plane of the channels 30.

The element 29 is arranged so that air under pressure supplied through manifold 34 to the feed slit 32 flows along the channels 30 to mouths 36 and in doing so im parts a longitudinal force by momentum transfer to the yarn passing through each channel. The air flow emerging from the mouths 36 become attached to surfaces 38 and 40 by a wall attachment or Coanda effect, and, if the portion 44 of a yarn is slack, causes the yarn to lie alongside the surfaces 38 and 40, as shown 44' in FIG. 3. The dimensions of the channels 30 will depend largely on the pitch of the warp yarns, the width of each channel being, e.g. two-thirds of the pitch whilst the di viding walls between the channels are of thickness equal to one-third of the pitch, and the deptch of each channel three to six times its width.

Each section of the array 14 consists of a stack of similar fluidic elements 60 (see FIG. 2) each of which is formed with multiple channels 62 each of which can accommodate one of the warp yarns 20. Each channel 62 has cross-sectional dimensions the same as those of each channel 30, and the channels 62 in each element 60 are provided with a common feed slot 64 leading from a manifold 66 in a similar manner to the element 16. The feed slot 64 is arranged so that supply of air under pressure from manifold 64 causes air flow along channels 62 to produce a longitudinal force on each warp yarn passing through the channel in a direction opposite to that of the force produced by air flow in the channels 30 of element 29.

The feed rollers 10 and take-up roller 26 are driven in synchronism in such a manner that the length of each warp yarn 20 which is held between the feed rollers and the fell 46 of the woven fabric has a predetermined length of slack. When air is supplied to channels 30 to create longitudinal force on the yarns passing through them. each yarn which is not restrained by a counter force produced by air flow in one of the elements 60 will be moved by the longitudinal force so that the slack is located in the shedding area. The slack yarn in the shedding area will take up a position alongside surface 38 and 40, as described above, and so will be separated from the warp sheet to form a shed for the passage of a weft carrier 22, as shown in H6. 2. When force is applied to the yarn is the opposite direction, by means of air flow through the appropriate element 60, the yarn will be moved so that the portion in the shedding area will be held in tension, and the slack in the length of yarn will in effect be transferred to a position between the element 60 and the feed rolls 10. Each element 60 is formed with a cavity 68 sufficient to accommodate the slack yarn 72, and a transverse pin 74 is so positioned that the slack yarn, carried away from channel 62 by the air flow from it, arranges itself in a loop between the pin 74 and one side of element 60, as shown at 72 in FIG. 2, to prevent tangling of the slack yarn.

It will be appreciated that by creating fluid flow alternately in channels 30 of element 29 and channel 62 of an element 60 the yarns passing through those channels will be reciprocated so that the portion 44 of each yarn in the shedding area will be alternately held in tension, so as to lie in the warp sheet plane defined by the portions 44 held in tension, and slackened and separated from the warp sheet to form a shed as shown at 44. It will be apparent that by maintaining fluid flow in the channels 62 of one or more of the elements 60 during the period when fluid is also supplied to channels 30 of element 29, yarns passing through the channels 62 in those elements will be preventing from moving to form sheds. The air supplied to channels 62 is preferably at a higher pressure than that supplied to channels 30, to ensure that the yarns are prevented from moving. Thus, by maintaining air supply to one or a combination of the element 60 during the shedding operation, the warp yarns shed are selected in a manner analogous to mechanical dobby control in a conventional loom, the warp yarns having been divided in a preselected manner between the elements 60 during loading of the yarns into the loom. It will be appreciated that, since all the yarns in any one element 60 always move together, the dividing walls between the channels 62 could be dispensed with, the channels being combined into a sin gle channel.

The weft carrier transport mechanism comprises a V-shaped track 42 which forms the stator of a synchronous linear induction motor, each weft carrier 22 forming a rotor of the motor. The upper flat faces 40 and 41 of the two slides and 81 forming the track are perpendicular to one another, and beneath each slide is a series of propulsion coils (82 and 84) arranged in a continuous line, the axis of each coil being perpendicular to the corresponding face 40 or 41. Each weft carrier 22 is formed from a combination of a ferromagnetic material, such as iron or nickel, and a non-ferromagnetic conductor, such as aluminium, held in a moulded plastics body, in such proportions that in use the forces of gravity and of attraction of the ferromagnetic material by the magnetic field of the propulsion coils is balanced by the repulsion due to the interaction of the magnetic propulsion field with the magnetic field produced by eddy currents induced in the conducting material so that the carrier is stably supported at a short distance above the faces 40 and 41 of the track. As shown in FIG. 3, the axes of coils 80 and 8] intersect above the axis of the weft carrier 22 in its stable position, and this arrangement gives lateral stability to the carrier. During its flight the forces of repulsion generated by coils 80 and 81 produce turning movements of opposite sense on the carrier 22, which has a square cross-section, as shown in FIGS. 2 and 3.

To obtain synchronous movement of the weft carriers, coils in adjacent zones on the track are supplied with 3-phase current in such a way that the supply to the leading zones generates a magnetic field urging the weft carrier in one direction whilst the supply to the lagging zones generates a field producing an opposing force, so that the weft carrier is held stably between the fields. The fields are stepped along the track at the desired weft carrier speed, by a suitable commutation arrangement switching the currents at a frequency less than the frequency of the three-phase supply, so that the carrier is propelled stably at the desired speed. The supply of current to the coils is controlled so that travelling fields are similarly generated and pitched along the track at the desired spacing between successive weft carriers.

The weft carriers are fed to the track 42 from one or more feed devices 90. Each device 90 has a hopper 92 which is supplied with weft carriers 22 from a suitable filling mechanism in which each carrier 22 is filled with a weft yarn of predetermined length. A photocell and lamp arrangement 94 provides a signal to cause the hopper to be filled when the number of carriers in it falls below a fixed level. At the lower end of hopper 92 the weft carriers are gripped by two spiral feed cams 96 which engage in longitudinal grooves 98 (FIG. 3) in the sides of the weft carriers. The cams are driven by a stepping motor 100 which, in response to a control signal, rotates the cams through one revolution to advance the warp carriers 22 by one width. The last 180 of each spiral cam is toothed, as shown at 102 in FIG. 5. The teeth engage, during each revolution of the cams, corresponding teeth formed in the grooves 98 of the lowermost weft carrier 22, so that as the carrier is released from the cams onto the track 42 it is given a forward velocity approximately equal to its flight velocity along the track. The operation of stepping motor 100 is synchronised with that of the weft carrier transport fields traveling along track 42 so that successive weft carriers are projected onto the track 42 at the appropriate frequency.

A number of weft carrier feed devices may be provided in parallel, and may be supplied with weft carriers loaded with different coloured yarns, to enable the different coloured weft yarns to be inserted in accordance with a programme derived, for example, from a punched tape reader or a small tape recorder.

Each weft yarn carrier is designed so that the yarn is paid out from the rear of the carrier during its flight through the loom, the yarn being paid out through a spring release device which allows any knotted or tangled portion of yarn to escape from the shuttle without the build up of a high tension in the weft yarn which would arrest passage of the carrier across the loom. A suitable mechanism (not shown) is provided at the entry of the shedding area to pick up the tail of the weft yarn protruding from each carrier as the carrier passes the mechanism at the beginning of its travel across the loom, and to fasten the end of the yarn in any suitable manner into the selvedge of the woven fabric. For example, this might be done by arranging a number of thermoplastic warp yarns at the edges of the warp sheet, and employing a mechanism to turn over the tail of the weft yarn onto the thermoplastic yarns and applying heat and pressure to cause the weft yarn to become secured to the thermoplastics yarns.

The beating mechanism 24 comprises a rotatable shaft to which is fixed a comb 112 arranged in a two start helix of pitch equal to the spacing between weft carriers. The comb is formed of radially extending lamellae or fingers 114 of deformable wire, arranged at a spacing equal to that of the channels 30. The shaft 110 is rotated at such a speed that the fingers 114 become inserted between adjacent warp yarns, after clamp 45 has been actuated to hold the yarns in tension, the fingers pressing the inserted weft yarn against the fell 46 of the fabric. The fingers are guided as they enter the warp sheet by grooves formed in the surface 39 of element 16. The fingers 114 are bent by engagement with fell guard 50 as they leave the warp sheet. The fell guard 50 and the clamp 45 may also be made resilient to provide resilience to the beating operation and control the force by which the weft yarn is pressed against the fell.

In operation of the loom, the shedding operation is carried out in each section, consisting of an element 29 of array 16, in turn, the shedding progressing synchronously with the beating operation and weft carrier travel, in effect in a discontinuous wave motion across the loom. In each section, the selected warp yarns are moved to form sheds, as described above, and a weft carrier, travelling in synchronism with the shedding wave, passes through the sheds, laying a weft yarn in them. The warp yarns are then moved in the opposite direction to draw all the warp yarns in the shedding area into tension, so that the weft yarn is held in position, interwoven into the warp yarns. The clamp 45 is then actuated to hold the warp yarns whilst the fingers of the beating comb move into the warp sheet and force the weft yarn against the fell of the woven fabric. The clamp 45 is then released, while the take-up roller 26 and feed roller 10 progress by an amount dependent on the density of the woven fabric. The next shedding operation is then begun.

The relative timing of the warp shedding, weft insertion and beating operations is illustrated in FIGS. 6 to 8. FIGS, 6 and 7 are diagrammatic sectional and plan views respectively of the shedding area at one instant in operation. It will be seen that the selected warp threads 20 in two adjacent sections and 122 are fully shed as the weft carrier 22 passes those sections. At the same instant those warp yarns in sections 124 and 126 which had been previously shed and through which the weft yarn 130 has been laid have been moved back into the warp sheet so that the weft yarn 130 is held between the warp yarns which are held in tension. In section 126 the beating of the weft yarn has been completed, as illustrated in FIG. 7. The sections of warp yarn between sections 122 and 124 are at intermediate stages in the process of being moved from the shed position to the unshed position. Sections 134 and 132 of the warp yarn, separated by one phase" of the multiphase shedding motion from the sections 120 and 122 similarly include fully shed yarns, and the next succeeding weft carrier 22' is positioned in the sheds 132, 134. The sections between sections 126 and 132 show warp yarns at intermediate stages in the shedding operation. It will be appreciated that the sheds formed by warp yarns in the different sections in effect travel in waves across the loom, with the beating operation and weft carrier travelling in synchronism with the shedding.

Fig. 8 is a timing cycle diagram illustrating the relative timing of the various operations on one section of the warp sheet. Line A shows the periods during which the fingers of the beating combs are inserted between the warp yarns of the section, line B shows the periods during which a weft carrier is passing the section, line C shows the periods during which the clamp 45 is actuated to hold the warp yarns in the shedding area in tension during the beating, line D shows the periods during which air is supplied to channels 30 in element 29 to effect shedding of the unrestrained warp yarns, and lines E and F show the periods during which air is supplied to the channels 62. It will be seen that in the period from t to when air is suppled to channels 30, air is supplied to the channels 62 in selected ones of the elements 60, as indicated on line B, to restrain the yarns in those elements, whilst the yarns in the remaining elements to which, as shown by line F, no air is supplied are not restrained and are therefore moved to form sheds. During the period from to when the supply of air to channels 30 has been cut off, air is suppled to all the elements 60, so that the shed yarns are withdrawn and all the warp yarns in the shedding area are then held in tension.

The loom can be provided with various faultdetecting devices to ensure reliability of the loom in operation. For example, a conventional drop wire arrangement 260 is provided between the warp beam 12 and feed rollers to detect broken warp yarns and provide a signal to stop the loom. The weft carrier filler mechanism can be provided with devices for detecting faults, such as a weft yarn of incorrect length or a yarn which has been drawn completely into the carrier leaving no protruding portion to be picked up by the selvedge mechanism, and providing a control signal to the shedding control system to delay shedding by one cycle whilst the faulty weft carrier travels across the loom, so that the passage of the faulty weft carrier does not affect the weaving operation.

It will be appreciated that the described loom operates a low level of forces applied to the warp yarns, thus enabling the shedding operations to be carried out at greatly increased speeds, and giving great flexibility in handling the warp yarns, e.g. in switching from multiphase operation to single phase operation, as described below in connection with the embodiment of FIGS. 19 and 20.

Instead of a multiphase loom, the loom could be made as a single phase loom, or as a ribbon loom. Different forms of the shedding system may be preferable in the different looms.

FIGS. 9 to show diagrammatically various alternative forms of shedding control systems which could be used in place of the elements 29 and 60 of the embodiment of FIGS. 1 to 5.

FIG. 9 shows a fluidic element 200 formed with a number of separate channels 202 (corresponding to channels 30 and 62 in the embodiment of FIGS. 1 to 5) through each of which passes a warp yarn 20. The channels are separated from one another by parallel dividing walls, to avoid adhesion between yarns in adja cent channels. One or more feed slits 204 leading from manifolds 206 are provided to enable air flow to be created in channel 202 in the shedding direction, in similar manner to feed slit 32 and manifold 34 in element 29 of the embodiment of FIGS. 1 to 5, and one or more feed slits 208 leading from manifolds 210 can similarly be used to create fluid flow in the opposite direction. Two flat surfaces 214 and 216 extend from the mount 212 of channel 202 in such a manner that the air flow emerging from the mouth when air under pressure is supplied through feed slot 204 can become stably attached to either surface by a wall attachment or C0- anda effect, the surfaces joining the upper and lower walls of the channel through curves ofa suitable radius. To control the attachment of the air flow to the surfaces control slits 218 and 220 are provided on either side of the channel 202, the slots being gererally perpendicular to the channel and opening into the channel at a distance from the ount 212 of typically five to 10 times the diameter of the yarn with which the element is designed to operate. If, at the same time an air is suplied through a manifold 222 to feed slit 218, the air flow will become attached to surface 216. If air pressure is supplied through manifold 224 to feed slit 220 instead of slit 218, the flow will be switched from surface 216 to surface 214. The dividing walls extend to a line 228 in order to separate the air flow from that due to adjacent channels 202.

A warp yarn 20, a predetermined length of which is held between feed rollers (not shown) and a thread guide 50, can thus be reciprocated, as in the first described embodiment, to render the portion 44 in the shedding area selectively slack and in tension. When the portion 44 is made slack it can, under control of pressure supplied to manifolds 218 and 224, be parted from the warp sheet in one direction to form a shed for the passage of a weft yarn 230, or can be parted from the warp sheet in the opposite direction so that it is effectively prevented from forming a shed. The geometry of the shedding area is such that the yarn, when shed, is held in a stable position by the air flow. The selection of warp yarns to be shed for each werft insertion can therefore be controlled by controlling the supply of air to the manifolds 222 and 224 associated with each channel 202.

FIG. 10 shows an element 200 generally similar to the element 200 shown in FIG. 9, except that no use is made of the Coanda effect to cause shedding of the warp yarns. lnstead, the control slits 218 and 220 are so positioned that air flow from one slit will interact with the air flow from the mount of channel 202 produced by the supply of air from slit 204 to give, by a momentum exchange process, a resultant stable air flow which will cause the slack portion 44 of warp yarn 20 to form a stable loop on one side or other of the warp sheet, depending on which control slit is employed. In this case the surfaces 214 and 216 act only to guide the air flow, and may in some cases be dispensed with. It will be apparent that, in this embodiment, unlike that of FIG. 9, the loop formed on one side or other of the warp sheet will remain stable only whilst air is flowing from both feed slit 204 and one or other of the control slits 218 and 220, so that the controlling flow must be maintained throughout the shedding operation.

lnstead of applying pressure alternately to control slits 218 and 220, a continuous pressure can be applied to one control slit, to maintain a stable air flow normally on one side of the warp sheet, and a higher pressure be applied to the other control slit to switch the flow when required to the other side of the warp sheet, the flow returning to its initial position when the higher control pressure is removed.

The embodiment of FIG. 11 is similar to that of FIG. 9, except that surface 216 is cut back to extend coplanar with surface 214, and only one control slit 218 is provided. The surfaces are arranged so that the air flow emerging from each channel 202, when air is supplied through feed slit 204, becomes stably attached by Coanda effect to surface 214 in the absence of any controlling air flow through control slit 218. When air pressure is supplied to control slit 218 the air flow is detached from surface 214 and takes up a position, owing to interaction the air flow from slit 218 on the other side of the warp sheet. This embodiment has the advantage over those of FIGS. 9 and 10 of requiring only one controlling air flow and of giving greater access to the shedding area.

It will be appreciated that many other configurations of the shedding area can be used to obtain the required fluid flow to effect the formation of stable sheds in the warp yarns. Many configurations for obtaining stable fluid flows are well known from fluidics, e.g. in the design of fluid logic elements, and it has been found in practice that with many of these configurations the air flow is such that it will carry with it a slack yarn to form a stable loop or shed so that they can be adapted for application to the weaving loom described.

FIG.12 shows an embodiment in which the yarn guide 50 is arranged in a plane spaced vertically from that of the channel 202 so that each warp yarn is turned through I80 after leaving the mouth 212 of channel 202 before entering the yarn guide. In this case the geometry of the arrangement enables a stable loop to be formed in the shed yarn 44 by the air flow issuing from mouth 212 without the need to employ the Coanda effect or any auxiliary controlling air flow. This embodiment also enables beating of the inserted weft yarns to be carried out automatically as the shed yarns are drawn back through channel 202 after the shedding operations, the weft yarn being drawn back by the warp yarns against the inclined edges 228 of the dividing walls'between channels 202, so that the weft yarn is pressed against the fell 46 of the woven fabric. FIGS. 13 and 14 show alternative arrangements of the shedding area in which beating can be carried out by drawing the edge 46 of the woven fabric against the dividing walls 228 after the shedding and weft insertion operations.

FIG. 15 illustrates an arrangement in which shedding selection of the warp yarns is carried out in a manner similar to that of the embodiment of FIGS. 1 to 5, by inhibiting movement of selected threads during the shedding operation. In this case, the movement is restrained by a series of mechanical clamps 234 which may be operated by any suitable means,v e.g. pneumatic, electromagnetic, piezo-electric or magnetostrictive. Between portions 236 and 238 of channel 202, into which the feed slits 204 and 208 respectively open, are a series of bridges 240 under which the warp yarns can move freely. Each yarn can be arranged to pass over one or more of the bridges and when any one of the clamps 234 is operated to move it against the corresponding bridge each of the yarns passing over that bridge will be prevented from moving during the shedding operation. It will be apparent that by operating one or more of the clamps 234 during each shedding operation only preselected warp yarns will be shed, so that shedding selection can be controlled in a manner analogous to dobby control in a conventional loom. It will be appreciated that in the embodiment of FIG. 15 the feed slit 208, supply of air through which draws into tension the yarn portions 44 i the shedding area, can be arranged to feed all the channels 202 in the section of the loom (or the whole loom in the case of a single phase loom) since it plays no part in shedding selection.

FIG. 16 shows an arrangement in which a dobby-type of shedding selection is employed in a shedding system similar to that of FIG. 11. The control manifold 222 of each element 200 is connected through branched feed channels 244 in a wafer block 242 individual to each channel 202 to a number of manifolds 246. The channels 244 are shaped so that air under pressure supplied to any one of the manifolds 246 will flow to the control manifold 222 without returning to any of the other manifolds 246. A block 248 fits over the blocks 242 and is formed with manifolds 250 each of which extends over the corresponding manifolds 246 in all the blocks 242 in one section of the loom (or over the width of the loom in the case of a single phase loom). A perforated paten 252 fits between the block 248 and blocks 242, the perforations in the platen connecting each common manifold 250 to selected ones of the manifolds 246. In operation, a command pressure signal is supplied to one or more of the common manifolds, the pressure being applied through perforations in platen 252 and feed channels 244 to selected ones of the control manifolds 222, cause shedding of selected warp yarns. The supply of air under pressure to common manifold 250 can be controlled, for example, by pneumatic control valves, under programmed control by a punched tape reader or small tape recorder or conventional dobby programming unit. The platen 252 can be replaced with a platen having a different arran-- gemennt of perforations, to vary the dobby control.

In a multi-phase loom, instead of providing a dobbytype pneumatic control mechanism as shown in FIG. 16, the shedding selection could be controlled, where the pattern of the weave is repeated regularly across the width of the fabric, in response to data stored in electronic or pneumatic logic devices. To this end, each control manifold 222 is connected to a supply of air under pressure through a diaphragm valve or fluid logic element, which is controlled in response to a timing signal and from a signal from a register, such as an electronic or pneumatic shift register, containing data defining the shedding selection.

A series of registers is provided, each arranged to control the operation of the shedding elements over a length corresponding to the pattern repeat length, and each register is adapted, in response to the timing signal, to transmit the data stored in it to the next register in line, so that the data defining the weaving pattern need initially be supplied to only one of the registers.

Since, in the embodiments of FIGS. 9 to 11, a separate control manifold 222 (or manifolds 222 and 224) is provided for each warp yarn channel 202, looms incorporating these embodiments are susceptible to fully programmed control of the warp shedding, in the manner of a Jacquard loom. It will be appreciated also that in the embodiment of FIGS. 1 to 5 and FIG. 15, where shedding selection is attained by inhibiting shedding movement of selected warp yarns, it would be possible, instead of the dobby-type controls described, to pro vide individual braking devices for each warp yarn, in which case these embodiments would similarly be susceptible to fully programmed shedding control.

FIG. 17 and 18 illustrate an embodiment in which fully programmed shedding control is applied to a loom having a shedding mechanism in which each warp yarn is shed only when pressure is applied to the corresponding control manifold 260. The manifold 206, through which air under pressure is supplied to channel 202 to produce shedding movement of the yarn 20, is connected to control manifold 260 through channels 262 and 264, and the junction of channels 262 and 264 is connected to a control port 266. When control port 266 is closed, pressure applied to manifold 206 will cause pressure to be simultaneously applied to control manifold 260, so that the corresponding warp yarn will be shed, whereas if port 266 is open the pressure applied to manifold 206 will not be transmitted to control manifold 260 and the warp yarn will remain unshed. The control ports 266 associated with each channel 202 are arranged in line across the loom, as shown in FIG. 18, and are covered by a metal sheet or roll 268 which is movable by means of a stepping motor in a direction perpendicular to the line of ports, and is maintained in register with the ports by ribs 270 engaging in grooves in the control elements. The sheet is formed with apertures, such as aperture 272 arranged in a pattern such that, after each stepwise movement of the sheet an aperture is in register with each control port 266 associated with the warp yarns which are not to be shed, so that those control ports are opened. The sheet or roll 268 can thus be patterned to provide a complete shedding programme for the loom.

It will be apparent that the shedding programme control could be carried out in various other ways, for example under the control of electronic or pneumatic logic circuits.

In the embodiment of FIGS. 9 and 10, a shed can in effect be formed in each warp yarn on either side of the warp yarn sheet. These embodiments can therefore be employed in a loom in which arrangements are made to enable each weft yarn to be inserted in sheds on either side of the warp sheet, weft insertion into the two sheds being simultaneous or successive as appropriate to the structure of the fabric to be woven and to the loom construction. This makes it possible, for example, to weave into the warp of a fabric special yarns, such as metal wires or elastic threads or fragile yarns, which cannot normally be handled by the pneumatic shedding techniques of the descrived embodiment, the special yarns being guided into the fell of the fabric along the plane of the warp sheet under the control of pinch rollers or other suitable feeding device, and held without slack, so that they remain taut in the shedding area.

The technique of double weft insertion is practically, but not exclusively useful in ribbon looms where double weft insertion can be conveniently arranged, and it enables, for example, elastic ribbons to be woven on a loom employing the shedding techniques described above.

It is also possible using double weft insertion as described, in combination with the flexible shedding control described above, to weave specialised fabric structures, for example fabric with a different texture on each of its two sides, or with a different woven coloured pattern on each side of the fabric.

FIGS. 19 and 20 shown a further embodiment of a multiphase loom in which beating is carried out by reciprocating reed elements. As shown in FIG. 19 and 20, a weft yarn carrier is transported through a shedding area 302, transport and leviation of the weft carrier being provided by a synchronous linear induction field generated by coils 304. Above the path of the weft carrier is a reed 306 consisting of a series of blocks 308 fixed to and supported by a flexible sheet 310 which is fixed at its upper margin to the frame 312. Each block 308 can be reciprocated by means of a hydraulic or pneumatic piston and cylinder device 314 individual to each block, the flexible sheet 310 allowing adjacent blocks 308 to pivot against each other so that the blocks can be moved in turn in a wave motion across the loom, as illustrated in FIG. 20. Each block is rearwardly tapered as shown at 350 to accommodate the relative pivoting of adjacent blocks, whilst the flexible sheet 310 maintains a continuous forward surface on the reed. Each block is normally held in its retracted position by a spring 316 acting on the piston of device 314.

Each block 308 contains a number, typically 20 to 100, of channels 318 through lack of which passes a warp yarn. The channels 318 correspond to channels 32 in the elements 29 of the embodiment of FIGS. 1 to 5, and the channels 318 in each block are similarly provided with a common feed slit 320 through which air under pressure can be supplied through a manifold 322 to channels 318 to produce a longitudinal force on the warp yarns in the channels urging them in the shedding direction A flexible sheet 326 is fixed at its upper margin to the lower margin of reed 306 and at its lower margin to the frame 312, and the shedding area 302 is shaped so that the air flow emerging from the mouth 324 of channels 318 when air is supplied to manifold 322 becomes attached to the surface of sheed 326, so that slack portions 44 of warp yarns in the shedding area are driven to form sheds for the passage of a weft carrier 300.

The warp yarns are driven from a beam through feed rollers and through a dobby-type arrangement 14' of fluidic elements in the same way as the embodiment of H68. 1 to 5, and a clamp 45 is similarly provided to clamp the warp yarns during beating.

In operation, after a weft carrier 300 has passed through sheds formed in warp yarns passing through channels 318 in one of the blocks 308, air pressure is applied to the manifolds in the dobby elements to begin withdrawing the shed warp yarns. At the same time the piston and cylinder device 314 is actuated to move the block 308 towards the fell of the woven fabric. When the yarns have been withdrawn so that the portions of yarn in the shedding area are in tension, clamp 45 is actuated to clamp the yarns. The process is timed so that this occurs just before the block 308 reaches the fell of the fabric to effect beating of the inserted weft yarn. When beating has been completed, pressure to device 314 is relieved so that the block begins to move back to its retracted position. At the same time, clamp 45 is released, and air is supplied to manifold 322 so that shedding of those warp yarns which are not held by dobby 14 can take place as the block is being retracted. When the block is in its fully retracted position the sheds formed are positioned to allow passage of the next weft carrier.

The relative timing of the various operations is the same as that shown in FIG. 8, the line A representing the periods during which the piston and cylinder devide 14 is actuated.

It will be appreciated that the shedding and beating operations travel effectively in waves across the loom, the timing of the actuation of the piston and cylinder devices 314 being in antiphase with the travel of the synchronous linear induction fields effecting weft carrier transport.

In the embodiment of FIG. 21, the weft carriers 300 are supported and transported by a synchronous linear induction field generated by coils 304. The general configuration of the shedding area, and the warp yarn dobby system and clamping brake 45 are similar to those of the embodiment of FIGS. 19 and 20. However, in this case the shedding manifold 322 and feed slit 320 are formed in a stationary member 303, the slit 320 opening into a cylindrical surface 332 on the stationary member. The reed 306' consists ofa series of shims 334 fixed in parallel planes and moulded or fixed in a rubber block to form an integral structure in which adjacent shims can be moved relative to one another through a small distance by virtue of shear deformation of the rubber between them. The reed 306 is rotatable about a pivot shaft 336, and each shim 334 has a curved outer edge 338 moving at a small distance say 2550 M, from the cylindrical surface 332. The curved outer edges 338 extend a short distance above a curved surface of the rubber block, so that adjacent shims 334 define between them a channel for the passage of a warp yarn, the feed slit 320 opening into all the channels. The overall structure of reed 306 has sufficient flexibility to enable the shim, the beating edge of which is shown at 334, in one section of the reed to be in a retracted position. as shown in FIG. 21, whilst the corresponding shim, the beating edge of which is shown at 334a, at a distance of one half wavelength away is in the forward position at which beating of an inserted weft yarn is completed. The reed is actuated in a wave motion by a series of piston and cylinder devices 314, or by a cam or other suitable mechanism.

The embodiments of FIGS. 19 to 21 incorporate a reciprocating reed system have the advantage that shedding and withdrawal of the warp yarns take place while the reed elements are moving, so that the beating operation does not take up a great deal of the overall cycle time of the weaving operation, and the various operations are kept in precise phase relationship. Since the reed elements reciprocate over only a short distance, the forces involved are at a low level, and since, owing to the wave motion, corresponding parts of the reed at any instant are moving in opposite directions the net linear momentum of the whole reed is practically zero. These arrangements of beating avoid the problem which arises in the embodiment of FIGS. 1 to of ensuring that the beating combs must remain in register with the channels 30 as they enter the warp sheet. They have the advantage furthermore that they can be operated in a single phase, so that, for example, if a faulty weft yarn occurs in a multiphase operation, the loom can be halted, temporarily converted to single phase operation, and several weft yarns to be removed until the faulty yarn is removed.

The embodiment of FIG. 21 has the further advantage that, by removing the stationary part 303, the warp yarns can easily be laid directly into the channels 332 before the part 303 is replaced.

Each of the looms of the described embodiments have the advantage that warp shedding is performed by means having a low increase, compared with conventionally used healds and beams, so that higher shedding speeds and lower reciprocating forces on the yarns can be employed. The looms have great flexibility, being susceptible to both dobby-type control and fully programmed control. The shedding system can be entirely or largely free from moving parts, giving good mechanical reliability as well as a low occurrence of warp yarn breakage. The construction of the shedding system is suitable for mass production, employing, for example, the photo-ceramic techniques used in fluid logic element construction, photo-etching or spark erosion from the dividing walls between channels in which the yarns move.

It will be appreciated that the present invention can be applied to looms of construction other than those of the described embodiment, and that the yarn-handling mechanism of the present invention might find application in other textile machines, such as knitting machines.

We claim:

]. A loom comprising:

a shedding section;

feeding means for feeding a plurality of warp yarns to said shedding section;

first and second gripping means for gripping a length of each one of said plurality of warp yarns, extending between said first and second gripping means, so that each length of warp yarn has a predetermined amount of slack;

a plurality of fluid flow means associated with respective ones of the lengths of warp yarn for creating gaseous fluid flow along at least one portion of each of the lengths of warp yarn, thereby applying longitudinal force to each length of yarn;

application of the longitudinal force in a first direction urging the length of yarn to be held in tension in said shedding section while a slack portion is formed at a second location remote from said shedding section, and application of the longitudinal force in a second direction urging the length of yarn to move so that a slack portion is formed in said shedding section while the yarn is held in tension at said second location;

a plurality of forming means associated with each of said fluid flow means, for forming the slack portion in said shedding section into a shed for the insertion of a weft yarn; and

shedding control means for controlling the shedding operation, by causing said plurality of fluid flow means to form a slack portion in each of said plurality of warp yarns in the shedding section according to a predetermined sequence.

2. A loom according to claim I, in which each of said plurality of fluid flow means comprises:

a plurality of channel means, each having an outlet opening into said shedding section, for passing a respective one of each of said plurality of lengths of warp yarn through;

a plurality of first inlet port means, opening into each of said plurality of channel means, such that a sup 

1. A loom comprising: a shedding section; feeding means for feeding a plurality of warp yarns to said shedding section; first and second gripping means for gripping a lengtH of each one of said plurality of warp yarns, extending between said first and second gripping means, so that each length of warp yarn has a predetermined amount of slack; a plurality of fluid flow means associated with respective ones of the lengths of warp yarn for creating gaseous fluid flow along at least one portion of each of the lengths of warp yarn, thereby applying longitudinal force to each length of yarn; application of the longitudinal force in a first direction urging the length of yarn to be held in tension in said shedding section while a slack portion is formed at a second location remote from said shedding section, and application of the longitudinal force in a second direction urging the length of yarn to move so that a slack portion is formed in said shedding section while the yarn is held in tension at said second location; a plurality of forming means associated with each of said fluid flow means, for forming the slack portion in said shedding section into a shed for the insertion of a weft yarn; and shedding control means for controlling the shedding operation, by causing said plurality of fluid flow means to form a slack portion in each of said plurality of warp yarns in the shedding section according to a predetermined sequence.
 2. A loom according to claim 1, in which each of said plurality of fluid flow means comprises: a plurality of channel means, each having an outlet opening into said shedding section, for passing a respective one of each of said plurality of lengths of warp yarn through; a plurality of first inlet port means, opening into each of said plurality of channel means, such that a supply of fluid under pressure causes flow of said fluid in said first direction through said channel means; and a plurality of second inlet port means, opening into each of said plurality of channel means, such that a supply of fluid under pressure causes flow of said fluid in said second direction through said channel means.
 3. A loom as claimed in claim 2 in which said forming means comprises flow control means for controlling the gaseous fluid flow at said outer opening to form a shed with said slack portion in said shedding action.
 4. A loom as claimed in claim 3, in which said flow control means comprises: a surface extending from said outlet opening of said channel means, said surface being inclined to the longitudinal axis of said channel in said shedding section, so that gaseous fluid flow in said second direction becomes attached to said surface by Coanda effect and urges said slack portion of the yarn to lie alongside said surface thereby forming a shed.
 5. A loom as claimed in claim 3, in which said flow control means includes a first auxiliary gas flow means for creating an auxiliary fluid flow which interacts with the gaseous fluid flow in said second direction thereby creating a net flow at said outlet opening of said channel which acts on said slack portion to form a shed.
 6. A loom as claimed in claim 5 wherein said shedding control means includes at least one control port through which fluid can be supplied to a second auxiliary gas flow means to cause the fluid flow from said outlet opening to be detached from said surface and to change the position of said slacked portion of said warp yarn to a position opposite to that of a shed.
 7. A loom as claimed in claim 6, further including: a second surface extending from said outlet opening on the side of said outlet opening opposite from said first surface; and control ports connected to said channel means through which fluid can be supplied to cause the fluid flow from said outlet opening to become detached from said first surface and attached to said second surface, thereby to change the position of the slack yarn to a position opposite that of a shed.
 8. A loom as claimed in claim 6, in which means are provided for introducing yarns into said shedding section which are held by further gripping means without slack and so are restrained from shedding.
 9. A loom as claimed in claim 2 in which said forming means comprises: said plurality of fluid flow means; a conduit means disposed adjacent each of said channel means, for substantially reversing the direction of travel of each of said plurality of lengths of yarn as it passes between said channel means and said first gripping means, such that when each of said plurality of lengths of yarn are urged in said second direction said slack portion forms a shed.
 10. A loom as claimed in claim 1 in which said shedding control means includes: reverse fluid flow means for creating fluid flow in said first direction along at least one portion of a plurality of adjacent warp yarns; and braking means, acting on each one of said plurality of adjacent warp yarns, to inhibit the movement thereof and thereby preventing the formation of a shed by each of said plurality of adjacent warp yarns, said braking means acting on selected groups, each containing a plurality of adjacent warp yarns, under the control of said shedding control means.
 11. A loom as claimed in claim 10, in which said braking means comprises mechanical clamps disposed to grip the selected yarns.
 12. A loom as claimed in claim 11, wherein said braking means includes: a plurality of clamps each disposed to act simultaneously on a selected one of said groups of the yarns, and said shedding control means effects operation of one or more of the clamps simultaneously.
 13. A loom as claimed in claim 10, in which said braking means comprises a further reverse fluid flow means for creating gaseous fluid flow over at least one portion of each warp yarn, thereby creating a longitudinal force in said first direction, thereby inhibiting formation of a shed.
 14. A loom as claimed in claim 13, in which braking means comprise a plurality of fluid flow elements each containing channel means through which can pass selected ones of the plurality of warp yarns, and the shedding control means is operable to create simultaneous fluid flow past the portions of the yarns passing through any one of the fluid flow elements thereby to inhibit shedding movement of those yarns.
 15. A loom as claimed in claim 1 in which said shedding control means selectively controls the flow of gaseous fluid to said plurality of fluid flow means and to said forming means, thereby controlling the shedding operation.
 16. A loom as claimed in claim 15, in which said shedding control means is controls the flow of fluid to one or more control parts associated with each said fluid flow means and each said forming means.
 17. A loom as claimed in claim 16, in which said shedding control means further includes: a plurality of control manifolds, each of which is connected to a selected group of said control parts associated with each of said plurality of control manifolds so that a supply of fluid to a selected one of said plurality of control manifolds effects supply of fluid to each of the associated group of control parts, said selected group of said control parts being generally different for each manifold; and means for supplying fluid selectively to one or more of said control manifolds.
 18. A loom as claimed in claim 17, further including platen means for changing the control parts which are associated with each of said plurality of control manifolds to alter the selection of the control parts connected to each of said control manifolds.
 19. A loom as claim in claim 1 in which said shedding control means controls the shedding of each of said warp yarns in a predetermined sequence in dependence on a predetermined program supplied to said shedding control means.
 20. A loom as claimed in claim 19, in which the shedding control means includes electronic or pneumatic logic circuits receiving data representing the shedding programme.
 21. A loom as claimed in claim 20, in which shed formation is timed to occur successively in said groups of adjacEnt warp yarns so that the shedding operation travels in a wave-like motion across the loom.
 22. A loom as claimed in claim 21, further including: a beating mechanism means for beating inserted weft yarns to form the fell of a woven fabric, said beating mechanism means comprising a rotatable shaft carrying one or more series of helically disposed fingers positioned so as to be inserted between adjacent warp yarns and to move between said warp yarns to beat said weft yarns as the shaft is rotated.
 23. A loom as claimed in claim 21, further including: a beating mechanism means for beating inserted weft yarns to form the fell of a woven fabric, said beating mechanism means including: a plurality of reciprocable reed-like elements, each of which defines a reed channel for the passage of a warp yarn, and said plurality of fluid flow means create a fluid flow in said second direction through said reed channels.
 24. A loom as claimed in claim 23, in which said fluid flow means includes at least one fluid flow port associated with each reed channel; and means for supplying fluid to said at least one fluid flow port.
 25. A loom as claimed in claim 23, in which said reed channels are defined by grooves formed in one surface of each of said reed-like elements and a stationary surface over which said reed-like elements move; and said fluid flow means includes a stationary member manifold with connections opening into said stationary surface.
 26. A loom as claimed in claim 1, in which means are provided for transporting a magnetically levitated weft carrier through the shed formed in the plurality of warp yarns.
 27. A loom as claimed in claim 1 in which there are provided clamping means operable to restrain movement of the warp yarns in the shedding area, after they have been drawn into tension by application of force in the first direction, during operation of beating means to pack the inserted weft yarn into the woven fabric.
 28. A yarn handling mechanism for a textile machine comprising: first and second gripping means for gripping a length of yarn extending between said first and second gripping means such that the length of yarn has a predetermined amount of slack; first fluid flow means for creating a gaseous fluid flow along at least one portion of the length of yarn, thereby applying longitudinal force in a first direction causing the yarn to be held in tension at a first location along the length of yarn extending between said first and second gripping means while a slacked portion occurs at a second location along the length of yarn; second fluid flow means for creating a gaseous fluid flow along at least one portion of the length of yarn, thereby applying longitudinal force in a second direction causing the yarn to be held in tension at said second location and a slack portion to occur at said first location; said first and second fluid flow means operating in conjunction with each other to cause a slacked portion of the length of yarn extending between said first and second gripping means to alternately occur at said first location and said second location; and positioning means at said second location for positioning said slacked portion of the length of yarn to form a shed, when said slacked portion is caused to occur at said second location.
 29. A loom comprising: a shedding section; feeding means for feeding a plurality of warp yarns to said shedding section; first and second gripping means for gripping a length of each of said plurality of warp yarns, extending between said first and second gripping means, so that each length of warp yarn has a predetermined amount of slack, a portion of each length of warp yarn extending through said shedding section; tensioning means for removing slack in selected ones of said plurality of said lengths of warp yarn in said portion of said length extending through said shedding section; a plurality of fluid flow means associated witH respective ones of said lengths of warp yarn for creating gaseous fluid flow along at least one portion of each of said lengths of warp yarn, thereby applying a longitudinal force to each length of yarn, causing each length of yarn not restrained by said tensioning means to form a slack portion in said shedding section; and means for selectively forming sheds from said slacked portions. 